We and others have previously shown that expression of mPGES-1, but not of cPGES, is elevated in articular tissues taken from patients with OA [16,17] and patients with RA [18], as well as in the rat adjuvant-induced arthritis model [19], suggesting that aberrant expression of this enzyme might contribute to the pathogenesis of arthritis. The gene discussed is PTGES3; the disease is arthritic joint disease.